fix(gateway): prevent --replace race condition causing multiple instances

When starting the gateway with --replace, concurrent invocations could
leave multiple instances running simultaneously. This happened because
write_pid_file() used a plain overwrite, so the second racer would
silently replace the first process's PID record.

Changes:
- gateway/status.py: write_pid_file() now uses atomic O_CREAT|O_EXCL
  creation. If the file already exists, it raises FileExistsError,
  allowing exactly one process to win the race.
- gateway/run.py: before writing the PID file, re-check get_running_pid()
  and catch FileExistsError from write_pid_file(). In both cases, stop
  the runner and return False so the process exits cleanly.

Fixes #11718

scripts/release.py

@@ -307,6 +307,7 @@ AUTHOR_MAP = {
     "anthhub@163.com": "anthhub",
     "shenuu@gmail.com": "shenuu",
     "xiayh17@gmail.com": "xiayh0107",
+    "zhujianxyz@gmail.com": "opriz",
     "asurla@nvidia.com": "anniesurla",
     "limkuan24@gmail.com": "WideLee",
     "aviralarora002@gmail.com": "AviArora02-commits",